Exhaust Valve Coloring?!

[cjserio]

Vehicle: 1994 D21 KA24E 4x4 with 170k miles....

So i'm reinstalling a new exhaust manifold and decided to take a peak at the exhaust valves while i'm cleaning the exhaust ports...I was suprised to see that the #1 and #3 cylinder's valves were black while the #2 and #4 cylinder's valves were white...

Is there something wrong with my engine or is there something about the way these engines work that i'm not aware of. I always thought black meant rich and white mean lean. How could each cylinder be receiving a different mixture? Why is it happening in pairs?

Cylinder #1

Cylinder #2

Cylinder #3

Cylinder #4

[480sx]

Its possible, but extremely unlikely that you have a blown HG.

I would say that your running lean on cylinder number 2 and 4. Your injectors could be clogged up. Might be a good time to send them out and get them serviced. Injector cleaner that goes in your tank does work though, to an extent.

[cjserio]

Hmm, if it were a headgasket, i think i would expect adjacent cylinders to be demonstrating the problem...not cylinders with some distance between them...I guess the most obvious problem would be injectors...Once i put everything back together and can release the fuel pressure, i'll take the injectors out and see.

I was mainly curious to see if anyone thought the valves looked abnormal. I know what they should look like on a lawnmower engine but this is the first vehicle engine i've worked on...They just seemed really really white and powdery.